a) Field of the Invention
The present invention is directed to a method and an arrangement for automatic detection, documentation and reproduction of the adjusted magnification in ophthalmologic instruments, particularly slit lamps. This is accomplished by means of a device which is arranged at the magnification changer and which supplies an electronically readable code depending on the optical component that is swiveled in.
b) Description of the Related Art
The slit lamp is one of the most common ophthalmologic instruments for examination of the eyes. It is particularly important for the ophthalmologist that an appropriate magnification can be adjusted depending on the area to be examined. In the known prior art, this is carried out by turning a knob which allows the corresponding magnification to be adjusted in individual steps by swiveling different optical components into the beam path. When the data gathered during an eye examination must be processed further, it is of particular concern that the adjusted magnification be documented. Generally, in ophthalmologic instruments an imaging scale is associated with (calibrated to) a determined magnification by a comparison scale. This magnification setting associated with the calibration value is reproducible by means of a scale with or without click-stop or locking positions. The adjustment is read off instantaneously at the rotating knob and is correspondingly noted.
A control device for a microscope by which the magnification as well as the focusing and illumination can be adjusted by means of electric drives is known from JP 02 191 909. As a rule, a data storage in which the required settings are stored is accessed by means of various switches.
EP 0 453 239 also describes an optical microscope with variable magnification in which the magnification is adjustable by means of a motor. In this case, starting from a desired image section, the maximum magnification is calculated and the corresponding lens system is introduced into the beam path by means of a motor. Among other things, the illumination intensity is adapted to the magnification simultaneously.
These solutions have the disadvantage that the adjustment of magnification is always coupled with the adjustment of focus and illumination. For ophthalmologic instruments, particularly slit lamps, this is not flexible enough since changes in magnification and/or illumination (intensity, color, pattern, etc.) are sometimes necessary during the examination.